Mute audio files for playback?
You were right. thx Polosson. :)

Step by step if you want to mute all audio files in your sequence editor:
1 Make your timeline visible
2 Click on Playback (You can find it on your timeline bar)
3 Choose "Audio muted" from the list and mark it.
If you want to back your audio audible, just unmark "Audio Muted"